A common architectural feature found particularly in residential homes is the vaulted ceiling. The vaulted ceiling is desirable in that it removes the claustrophobic nature of rooms such as formal sitting rooms and dining rooms which have a limited floor area as is commonly the case in many new housing developments where the amount of square footage of a dwelling is at a premium to the land developer. The sense of openness evoked by a vaulted ceiling is enhanced if tall windows are employed to take advantage of the higher than normal elevated walls, typically where a vaulted ceiling apex intersects a room wall. It is now well accepted that on such walls windows may be extended vertically by the use of correspondingly sized arched windows, that is, windows contained within generally semi-circular arched frames.
In the prior art, attempts have been made to provide retractable window blinds for use within such arched frames, none of which exhibiting the advantages of the present invention. A problem not properly addressed in the prior art is that in conventional arched windows, the centre of curvature of the window frame falls below the upper surface of the window sill. This occurs because, generally, the window frame is formed into a semi-circle, and the window sill having a discrete thickness is mounted between the opposite ends of the semi-circular arch thereby covering the center of curvature.